Plant for discharging wood



Dec. 7, 1954 Filed April 4, 1952 L. NORDSTROM PLANT FOR DISCHARGING WOOD 2 Sheets-Sheet 1 F I (LION; in

Dec. 7, 1954 1.. NORDSTROM PLANT FOR DISCHARGING woon 2 Sheets-Sheet 2 Filed April 4, 1952 United States Patent PLANT FOR DISCHARGING WOOD Leon N ordstriim, Stockholm, Sweden Application April 4, 1952, Serial No. 280,565 Claims priority, application Sweden April 4, 1951 4 Claims; (Cl. 214-85) Wood in the form of boards and deals or similar pieces which are to be dried artificially, is usually stacked in piles with intermediate laths. Such, piles may have a lateral dimension about 2 meters and a vertical dimension of about 3 meters, for example, and they are. stacked directly on cars which then are moved into drying houses. Recently, also for air drying in lumber-yards the wood is stacked in similar piles to be handled by crane trucks. The length of the piles should be somewhat greater than the maximum length of the boards or deals, but the boards ordeals are laid such that the piles get even end surfaces. Usually, five laths are laid between the individual layers of the pile, which laths'have a length equal to the lateral dimension of the pile and which are equally spaced from each other. When the wood lying on the cars in the drying house or lying in the lumber-yard is sufliciently dry, the wood is trimmed for shipping or storing. Now, the work comprising the discharging of the piles, delivering the boardswor deals of the piles and removing the laths has usually been performed by hand and has been very expensive.

The object of the invention is to create aplant for mechanically discharging wooden piles of said type so as to reduce the need of labourers and the time: required for the work, and a related object is to make said plant such that it is well suited for an automatic control.

According to a main feature of the invention such .a plant comprises two reversible conveyor systems spaced from each other in the direction of transportingfor producing between them a space of a width corresponding substantially to the maximum width of a board or: deal, said reversible conveyor systems being provided for feeding a pile alternatively in each direction over said :space to allow the boards or deals of the successively lowest layer of the pile to fall down in said space.

In a preferred embodiment one of said system is a stationary system of reversible conveyors arranged in parallel, and the other system also comprising reversible conveyors in parallel with, each other is vertically movable betwen an upper position above the level of the stationary system and a lower position below the level of the stationary system, said two systems being synchronously operated in each direction for feeding a pile from the stationary system over said space to said other system when in its higher position and feeding said pile from said other system when in its lower position back to the stationary system, and so on.

A preferred embodiment of a plant according to the invention is by way of example illustrated in the accompanying drawings, in which Fig. l is a plan of the plant, while Figs. 2 and 3 are vertical cross-sections on a greater scale, showing the vertically movable conveyor system in its higher position and in its lower position, respectively.

Each conveyor system 1 and 1, respectively, comprises a number of parallel conveyors 2 and 2', respectively, which could be belt conveyors but preferably are chain conveyors. The chain wheels 2 and 3', respectively, of said conveyors lying at the end nearest to the space 4 are securely mounted on a longitudinal driving shaft 5 and 5', respectively, coupled to a reversible electric driving motor 6 and 6, respectively, alongside the chain conveyors 2, 2', belt conveyors 7 and 7, respectively, are provided. The belt drums 7a and Ta of said belt conveyors lying at the outer and of the same are securely mounted on a driving shaft 9 and 9', respectively, said two shafts being provided with electrical driving motors "ice 10 and 10', respectively, which are independent of the motors 6, 6" for continuously operating the belt conveyors. Oppositev the belt drums 7b and Th of the belt conveyors 7,. 7' lying at the inner end of the same, grooved rollers 8 and 8, respectively, are securely mounted on the shafts 5, 5', which rollers receive the laths falling down and transfer the same to the belt conveyors disposed at a lower level. The belt conveyors 7, 7' will transport the laths to a point where they are used for stacking new piles of boards and deals or the like. In the space 4 a roller way 11 extends for the purpose of transporting the boards or deals falling down further to a trimmer saw or a store.

In" the stationary system 1 the frames of the chain conveyors 2 and the belt conveyors 7 are securely mounted on supports 12' and 13, respectively. In the vertically movable system 1' the frames of the chain conveyors 2, and the belt conveyors 7' together with shafts and driving motors are supported in a common frame 14 which is carried by four vertical screw spindles 15 engaging with screw sleeves secured in the frame 14. The screw spindles 15 are mounted in brackets 16 and are by means of associated chain wheels 17 and a drive chain 18 driven by a chain wheel 19 geared to the reversible electric motor 20. When operating the motor 20 in either direction the frame 14 together with the associated conveyors will be moved vertically either to a higher position: in which said frame is as much higher than the stationary system 1 as corresponds substantially to the thickness dimension of a layer in the pile, or to a. lower position in which said frame is as much lower than the stationary system as corresponds substantially to said thickness dimension.

When a pile to be discharged is obtained from a drying house it is delivered by means of the car carrying the same, and is then loaded upon the stationary conveyor system 1 by means of a telpher', a gantry crane or the like. A pile delivered from a lumber-yard by a crane truck, is by means of the same loaded directly on the stationary conveyor system 1. The piles are placed in such positions that the laths will lie approximately opposite the belt conveyors 7. A pile in such a position on the stationary conveyor system is shown in Fig. 2, in which A indicates the deals (shown in cross-section) and B indicates the laths. Assuming that the conveyor system 1' occupies its higher position (Fig. 2) and that the. chain conveyors 2, 2 of both systems are synchronously operated for feeding to the right in Fig. 2, the pile is conveyed over the space 4, the deals, A of the lowest layer of the pile falling down in the space 4 onto the roller way 11, while the laths B above this. layer are carried away by the remaining part of the pile and are pushed over to the conveyor system 1', where they finally fall down on the belt conveyors 7. After the chain conveyors 2, 2 have been stopped, the system 1' is lowered andthen the chain conveyors are started in the reverse direction, viz, to the left in Fig. 3. Now the remaining part of the pile is fed back over the space 4 and the deals of the layer now the lowest one fall down in the space onto the roller way. These operations are repeated until the entire pile has been discharged.

A plant of the type described can be controlled by hand but is especially well adapted for an automatic control. Such automatic control can easily be effected by means of limit switches which are provided for controlling the electric driving motors by means of magnetic contactors which in addition to the windings controlled from the limit switches have also push button switches for starting and stopping the driving motors at any desired time, for instance at the end of the working period, and the driving motors to be controlled are preferably three phase squirrel cage induction motors. The structure of limit switches and the circuit connections of the same and of magnetic contactors with associated elements are well-known in the art and do not constitute any part of the present invention. Therefore, a detailed illustration of said switches and other electrical elements with circuit connections is superfluous, it only being necessary to mention the function of the limit switches in order to allow anyone skilled in the art to design an electrical system performing the functions desired.

In the frame of the system 1 there is stationarily mounted a limit switch 25 the operation lever of which is actuated by the pile when completely fed onto the system 1. Said limit switch 25 stops both driving motors 6, 6 when the pile has been completely advanced to the right in Fig. 2, and at the same time it connects the driving motor 20 for lowering the system 1. In a similar way the system 1 has a stationary limit switch 26 the operation lever of which is actuated by the pile when completely fed onto the system 1. Said limit switch 26 stops both driving motors 6, 6 when the pile has been completely advanced to the left in Fig. 3, and at the same time it connects the driving motor 20 for lifting the system 1'.

Also a limit switch 27 actuated in dependence upon the operation of the driving motor 20 is provided, which at the completion of the lowering movement stops the driving motor 20 and starts both driving motors 6, 6' for feeding the pile to the left in Fig. 3, and which at the completion of the lifting movement stops the driving motor 20 and starts both driving motors 6, 6 for feeding the pile to the right in Fig. 2. The limit switch 27 which is a reversing switch may be stationarily mounted on a bracket at the side of the chain 18. The chain 18 is provided with two dogs 27' for actuating the switch 27 at the end of the lowering movement and at the end of the lifting movement, respectively.

The invention is not restricted to the embodiment as described and illustrated in the accompanying drawing, many modifications being possible without departing from the spirit of the invention.

What I claim is:

1. A plant for discharging wooden pieces in the form of boards or deals stacked in piles with intermediate laths, comprising two reversible conveyor systems spaced from each other in the direction of transporting for producing between them a space of a width corresponding substantially to the maximum width of a wooden piece, said reversible conveyor systems being provided for feeding a pile alternatively in each direction over said space to allow the pieces of the successively lowest layer of the pile to fall down in said space, a roller way in said space for further transport of the discharged wooden pieces, separately operated conveyors alongside said reversible conveyors for transporting away laths falling down, and grooved rollers in front of said separate conveyors for transferring laths falling down unto said separate conveyors.

2. A plant for discharging wooden pieces in the form of boards or deals stacked in piles with intermediate laths, comprising a stationary system of reversible conveyors arranged in parallel, and a vertically movable system of reversible conveyors arranged in parallel with each other, said two systems being spaced from each other in the direction of transporting for producing between them a space of a width corresponding substantially to the maximum width of a wooden piece and be ng synchronously operated in each direction, for feeding a pile alternatively in each direction over said space to allow the pieces of the successively lowest layer of the pile to fall down in said space.

3. A plant for discharging wooden pieces in the form of boards or deals stacked in piles with intermediate laths, comprising a stationary system of reversible conveyors arranged in parallel, and a second system of reversible conveyors arranged in parallel with each other, which second conveyor system is vertically movable between an upper position above the level of the stationary system, and a lower position below the level of the stationary system, said two systems being spaced from each other in the direction of transporting for producing between them a space of a width corresponding substantially to the maximum width of a wooden piece and being synchronously operated in each direction, for feeding a pile from the stationary system over said space to said second system when in its higher position to allow the pieces of the lowest layer to fall down in said space, and then feeding said pile from said second system when in its lower position back to the stationary system to allow the pieces of the layer of the pile now the lowest one to fall down in said space, and so on.

4. A plant for discharging wooden pieces in the form of boards or deals stacked in piles with intermediate laths, comprising a stationary system of reversible conveyors arranged in parallel, and a second system of reversible conveyors arranged in parallel with each other, which second conveyor system is vertically movable between an upper position above the level of the stationary system, and a lower position below the level of the stationary system, said two systems being spaced from each other in the direction of transporting for producing between them a space of a width corresponding substantially to the maximum width of a wooden piece and being synchronously operated in each direction, for feeding a pile from the stationary system over said space to said second system when in its higher position to allow the pieces of the lowest layer to fall down in said space, and then feeding said pile from said second system when in its lower position back to the stationary system to allow the pieces of the layer of the pile now the lowest one to fall down in said space, and so on, reversible electrical driving motors for operating the conveyors of said two systems and for moving the second system vertically, a limit switch in the second system operated by the pile and provided for stopping the driving motors of the conveyors ofboth systems when the feeding in one direction is completed and for connecting the vertical movement motor for lowering the second system, a limit switch in the stationary system operated by the pile and provided for stopping the driving motors of the conveyors of both systems when the feeding in the opposite direction is completed and for connecting the vertical movement motor for lifting the second system, and a limit switch in the second system operated in dependence upon the vertical movement and provided for starting the driving motors of the conveyors of both systerns for feeding the pile over to the stationary system when the lowering movement of the second system is completed, and for starting the driving motors of the conveyors of both systems in the reverse direction for feeding the pile over to the second system when the lifting movement of the second system is completed.

Country Date Great Britain Aug. 30, 1935 Number 

